Automatic emergency relevelling device for lifts



S. SGROI Sept. 30, 1969 AUTOMATIC EMERGENCY RELEVELLING DEVICE FOR LIFTS Filed May 8, 1967 United States Patent 3,469,657 AUTOMATIC EMERGENCY RELEVELLING DEVICE FOR LIFTS Salvatore Sgroi, 38 Via Ausonia, Palermo, Italy Filed May 8, 1967, Ser. No. 636,951 Claims priority, application Italy, May 9, 1966, 10,544/ 66 Int. Cl. B66b 1/50 U.S. Cl. 18729 12 Claims ABSTRACT OF THE DISCLOSURE The invention aims at dispensing with the need for providing a high power motor or large counterweight system for bringing up or down to a landing a lift car which has stopped between landings for untoward reasons. The invention relies on the use of a low power motor to displace the lift car either up or down in dependence upon the power capabilities of the motor. A reversing relay arrangement is provided to ensure that if this low power motor cannot displace the lift in one direction the power supply to the motor will be reversed and it will displace the lift car in the other and easier direction.

The invention relates to automatic emergency re-levelling devices for lifts, by which term it is intended to embrace all types of passenger and freight lifts and elevators, such devices being used to dispatch a lift car to the nearest landing in the case of accidental stoppage between two landings. Such stoppages may of course occur as a result of mains failure, faults in the lift circuits, or localised damage.

Emergency devices of the abovementioned type are known which are based on the use of an auxiliary, preferably direct current, electric motor which can be fed from storage batteries to operate the winch of the lift hoisting gear in order to move the car to the nearest landing door when it stops at a position removed from any floor.

Although known devices of this kind may be relatively simple in construction and relatively easy to install, they are objectionable in that they require at least one auxiliary electric motor and feed storage battery of power capable of handling a fully loaded lift.

With these objections in mind mechanically operating emergency devices have been proposed, which devices make use of the power available from an elevated auxiliary counterweight which is adapted to operate the winch of the plant and so move the lift car to the nearest landing. However, devices of this type are of necessity rather elaborate and of course require the installation of an auxiliary counterweight of considerable size and weight. It is also to be borne in mind that such a weight must be returned to its initial position after each or any occasion of use.

It is an object of the present invention to obviate the drawbacks of known devices of the two abovementioned types and to provide an emergency device which is simple and inexpensive in construction and which can be used with existing plants. it is a further object to provide a device which will fulfill all the above requirements while being safe, accurate and reliable in operation in the event of emergency use.

A still further object of the invention is to provide a device of the general abovementioned type which requires an auxiliary electric motor of only relatively low power, which power is independent of the capacity of the lift. It is an associated object to meet these requirements while dispensing with the use of a counterweight of size commensurate with the capacity of the lift.

3,469,657 Patented Sept. 30., 1969 According to these and other objects the invention consists in an automatic emergency re-levelling device for a lift car, wherein an emergency car operating circuit comprises an emergency car control means of relatively low power arranged to operate a winch for effecting vertical movements of the car, the said means being arranged to be automatically actuated as a result of accidental stoppage of the car between two landings and to effect re-levelling of the car to one of the said two landings by displacing the car in a direction which results in power requirements within the capabilities of the said low power means.

Generally, the power of the means is such that the car is displaced in a direction either up or down in dependence upon whichever requires the least effort.

Advantageously, the emergency control means comprises a direct current electric motor fed from a storage battery and the emergency operating circuit includes an electromagnet adapted to effect opening of a brake for the winch, first means being provided for maintaining the said emergency circuit open during normal operation of the lift by a normal operating circuit and for automatically closing it in the event of an emergency due to stoppage of the car between two landings, and further means provided for permitting operation of the motor on closure of the emergency circuit in that sense of rotation which results in displacement of the car in the said direction.

These and other objects and advantages of the invention will be clear from the following description, given with reference to the accompanying drawings which are by way of example and in which:

FIG. 1 is a circuit and schematic diagram showing an emergency device according to the invention in its inoperative position;

FIG. 2 is a similar diagram to that of FIG. 1 showing the device thereof dun'ng operation; and

FIG. 3 is a perspective view of both the normal and auxiliary or emergency control means for the lift car.

As shown in FIG. 3, a passenger or freight lift car 8 is normally controlled by a winch 35 operable in a known manner by an electric motor 36. A brake 37 is also shown which is urged into a closed or on position by spring means 38 but which may be opened or released" by an electromagnet 39. In FIG. 3 a counterweight 5 for the car 8 is also shown but no details are given herein of the operation of this well-known normal control means.

As shown in the two remaining figures, a rope 3 is wound on a pulley 2 which is freely rotatable on a pivot 1, one of the rope ends being connected to the counterweight 5 via a spring 4 and the other end to the lift car 8 via a spring 9. A plurality of cam means 10 are attached to the rope 3 in a predetermined spaced relationship and are so distributed therealong that a said means 10 is arranged on a predetermined portion of the pulley 2 whenever the car 8 is at any of the lift landings.

A level is fulcrumed at 12 to a fixed pivot and has a curved front arm 11a which is adapted to overlie a porton of the pulley 2 corresponding in the drawings to the top right quadrant thereof. The other or rear arm 11b of the lever 11 carriers two different operative positions of the lever with two sets of contacts 13a, 14a, to which contacts are connected an emergency operating circuit and the normal operating circuit of the lift, respectively. The latter circuit of course includes the aforementioned normal control means and the lever arrangement is such that in one position of the arm lla'the bridge 13 closes the contacts 13a while in another position thereof the bridge 14 closes the contacts 14a. The rear arm 11b of the lever 11 is biased by a spring 15 to urge the curved arm 11a towards and against the pulley 2, an electromagnet is itsef under the control of the normal operating circuits of the lift in a manner referred to in greater detail hereinbelow and is associated with a delay device 17.

When the car 8 stands at any lift landing, the lever 11 stops the position shown in FIG. 1, because one of the cam means 10 is automatically interposed between the pulley 2 and the curved arm 11a of the said lever. Consequently, the rear arm 11b of the lever is so positioned as to hold the contacts 14a closed and thus to permit normal operation of the plant. At this stage the contacts 13a of the emergency device are open.

As soon as the car starts to rise or fall, the cam means 10 leaves that pulley portion which is associated with the lever 11. The lever 11, however, remains in the position shown in FIG. 1 as a result of the action of the electromagnet 16 which has been energised through a parallel connection thereof with the circuit of the main fail-safe brake of the lifting winch.

If the car 8 stops away from a landing by a length equalling at least one half the arc of the pulley 2 associated with the curved portion 11a of the lever 11, no cam means 10 will be in a position to engage the lever 11. As the electromagnet 16 is now no longer energised (the car 8 having stopped and the brake 37 being on), the lever 11 will rotate about its fulcrum 12 under the action of the return spring and will attain the position shown in FIG. 2. This will occur within a period of time dependent upon the setting of the delay device 17 and such rotation of the level 11 will effect closure of the contact 13a of the emergency operating circuit and simultaneous opening of the contacts 14a of the normal operating circuit.

The emergency circuit comprises a storage battery 18 arranged to be buffer loaded and charged by an apparatus 19 and an electromagnet 20 arranged to effect opening of the brake 37 (FIG. 3). The circuit further comprises a direct current electric motor 25, of which latter motor the energising circuit brushes and the field windings are denoted 26a, 26, respectively. The brushes 26a are connected to two leads 23, 24 of the emergency circuit, the field windings 26 being connected to the same said leads via a reversing relay 27. This relay comprises a plurality of movable contacts adapted to connect to the leads 23, 24 either a first set of winding contacts 28, 29 or a second set of winding contacts 28', 29. Connection to the said first contacts results in rotation of the motor in one sense and connection to the other said contacts results in rotation of the motor in the opposite sense.

The relay 27 has two energising coils 30, 31, the coil 30 being connected in parallel with the connection between the field windings 26 and the lead 24, and the coil 31 being connected in series with the connection between the brushes 26a and the same said lead 24 via a thermal relay 32.

The shaft of the motor 25 of the emergency circuit is connected to the winch 35 either directly or (as shown in FIG 3) through clutch means and suitable drives in order to effect movement of the car 8 either up or down.

In use, the device operates as follows:

When, for any of the reasons instanced hereinbefore, the lever 11 moves into the position shown in FIG. 2, it closes the contacts 13a, and the storage battery 18 feeds the control resistor of the thermal relay 32 as well as the resistors of a similar relay 21. The battery also feeds the auxiliary motor 25 and an electromagnet 20 which is arranged to operate the winch brake 37 in the manner of the magnet 39, which latter may of course be without energising current. After this electromagnet 20 has opened the said brake 37 of the winch, the thermal relay 21 cuts in a limiting resistor 22 for reasons well known in the art.

Even though the auxiliary motor 25 is set in motion, the reversing relay 27 remains in the position shown in FIG. 1. This is because, although the armature current flowing would be sulficient to change over the said relay, the relay coil 31 is being short-circuited by the bimetallic strip of the thermal relay 32 and current is reaching the motor armature without passing through this coil.

If the power of the auxiliary motor 25 is sufficient to set the winch 35 in motion, in the direction dictated by the position of the relay 27, the motor will continue to rotate and the car 8 start its re-levelling travel to reach the nearest landing. Under these conditions the armature current for the motor 25 flows through the coil 31 of the switch relay, the bimetallic strip of the thermal relay 32 having in the meantime opened as shown in FIG. 2. This current alone is not however strong enough to effect attraction of the movable portion ofthe relay 27 and consequent relay change-over.

If the power of the auxiliary motor 25 is insufiicient to move the car in the direction dictated by the relay 27, the motor will stop and the armature current increase in intensity. This results in energisation of the relay coil 31 and consequently more substantial attraction of the movable portion of the relay 27 so that the contacts thereof are moved over into the position shown in FIG. 2. The polarity of the feed to the motor field windings 26 is thereby reversed and the sense of rotation of the said motor 25 is similarly reversed. This sets the winch 35 in motion in a reverse direction so as to move the car in the opposite direction.

The coil 30, which is now energised because it is in parallel with the field circuit 26 of the electric motor 25, intensifies the magnetic field created by the coil 31, thereby ensuring retention of the movable portion of the switch relay 27 in the adopted position despite subsequent diminution of the current through coil 31.

A centrifugal brake (not shown) is provided on the shaft of the auxiliary motor 25 to prevent overspeed of the car during operation of the emergency device.

When the car is at such a distance from the nearer landing that one of the cam means 10 on the rope 3 engages the lever 11, the contact 13a opens the emergency operating circuit and the motor 25 stops. The electromagnet of the brake 20 is de-energised and the winch is also stopped. The contact 14a is however automatically reclosed and the plant is again in order for normal operation.

In the event of breakage of rope 3 of the intervention of the safety brake for the car, operation of the emergency device is inhibited, whatever the location of the car may be. In either case the spring 9 rotates a lever 6 which is fulcrumed to a pivot 7 situated on the car roof, such rotation being in such a sense as to cause the closure of a contact pair 33 by a suitable bridge on the lever 6, such closure energising a relay 34 to break the emergency operating circuit. In order to ensure that the emergency device will not operate an over-run of the car, a plurality of further cam means can be secured to the rope 3, which further means follow the cam means 10 associated with the first and last stop. In this way it is ensured that the lever 11 will remain in the position shown in FIG. 1 even after the full permitted over-run of the car beneath the first landing stop and above the last landing stop.

The storage battery 18 can, of course, also be used for feeding alarm bells or a permanent emergency lighting plant in the car.

With the device hereinbefore described the energy available as a result of the difference in weight between the lift car and its load and the counterweight can be utilised. This is so because the motor 25 rotates to displace the car in a direction requiring only that power which is within the limited power-handling capabilities of the motor 25. In practice, of course, this is the least effort, because the essence of the invention is to dispense with auxiliary motors capable of moving the car in either direction. The auxiliary motor is in fact utilized primarily to overcome the passive and starting resistances of the plant, so that its power can be low and in any case unrelated to the size, weight and capacity of the lift plant.

Various modifications of the invention are, of course, possible within the scope of the appended claims.

For instance, the device can incorporate two separate auxiliary electric motors one for up and one for down travel, or even a motor or motors of other than electric drive.

What I claim is:

1. Automatic emergency relevelling device for a lift car comprising an emergency car operating circuit, which said circuit comprises an emergency car control means of relatively low power, the said device further comprising a winch for effecting vertical movement of the said car and the said emergency car control means being arranged to be automatically actuated as a result of accidental stoppage of the car between two landings and to effect relevelling of the car to one of the said two landings by displacing the car in a direction which results in power requirements within the capabilities of the said low power means.

2. Device as claimed in claim 1, wherein the said low power of the means is such that the said car is displaced in a direction either up or down in dependence upon whichever requires the least effort.

3. Device as claimed in claim 1, wherein the emergency control means comprises a direct current electric motor fed from a storage battery and the emergency operating circuit includes an electromagnet adapted to effect opening of a brake for the winch, first means being provided for maintaining the said emergency circuit open during normal operation of the lift by a normal operating circuit and for automatically closing it in the event of an emergency due to stoppage of the car between two landings, and further means provided for permitting operation of the motor on closure of the emergency circuit in that sense of rotation which results in displacement of the car in the said direction.

4. Device as claimed in claim 3, wherein the said first means comprises a swing lever having a" curved arm adapted to encircle in part a pulley freely rotatable on a stationary pivot, the said lever carrying "on its other arm an electrical bridge piece adapted in one of two operative positions of the lever to close the said emergency operating circuit and in the other of the said positions to close the normal operating circuit of the lift.

5. Device as claimed in claim 4, wherein spring means are provided which bias the said arm of the said lever thereby to urge the said lever into the said operative position thereof corresponding to closure of the emergency circuit.

6. Device as claimed in claim 5, wherein an electromagnetic operating means is provided, the said lever being acted upon by the said electromagnetic operating means which said means are connected with the normal operating circuit and which said means are adapted to retain the lever during normal operations of the lift against the action of the said spring means in the operative position thereof in which the normal operating circuit is closed.

7. Device as claimed in claim 6, wherein a rope is provided which rope travels over the pulley, and is connected both to a car counterweight and the said car, a plurality of cam means being provided on the said rope and so distributed thereon that when the car is at a landing one of the said cam means is arranged on that pulley portion encircled by the curved lever arm thereby to maintain the said lever in that position thereof in which the normal operating circuit is closed whether or not the electromagnetic operating means are energised, accidental stoppage of the car away from the landings and deenergisation of the said electromagnetic operating means effecting movement of the lever by the spring means into the position thereof corresponding to closure of the emergency operating circuit.

8. Device as claimed in claim 3, wherein a reversing relay is provided, the said electric motor being connected to the emergency operating circuit by the said reversing relay which relay is adapted to reverse the polarity of the motor supply and thus the sense of rotation of the said motor if the power requirements encountered on starting of the motor exceed the power capabilities of the said motor.

9. Device as claimed in claim 8, wherein the said relay is provided with energising coils adapted to be fed from the armature current flowing in the field circuit of the motor, the said coils being energised by the armature current to change over the said relay and reverse the current polarity when the said current exceeds a predetermined value corresponding to the power capabilities of the motor being exceeded by excessive resistance to car movement.

10. Device as claimed in claim 9, wherein a thermal relay is provided and the said reversing relay is provided with two separate coils, one said coil being series connected with the emergising circuit for the said motor via the said thermal relay which latter is adapted to shortcircuit the said coil at the beginning of the emergency operation and so prevent the passage therethrough of a current suflicient to change over the relay, and the other said coil being paralleled with the motor field winding so as to be de-energised after reversal of the polarity and to cooperate with the said first mentioned coil in order to maintain the relay position constant during the period of operation of the motor.

11. Device as claimed in claim 10, wherein means are provided for breaking the said emergency operation circuit in the event of breakage of the rope or activation of a lift safety brake, the said means comprising a switch operated by a swing lever fulcrumed on the car roof and connected with the said rope, the said switch controlling an electromagnet adapted to break the said emergency circuit.

12. Device as claimed in claim 1, wherein a clutch is provided between the emergency car control means and the winch, the said clutch being engaged by closure of the emergency car operating circuit.

References Cited UNITED STATES PATENTS 2/1955 Chiselbrook 187--29 8/1964 Tressel 187-29 

